xen: extend domctl interface for cache coloring

Add a new domctl hypercall to allow the user to set LLC coloring
configurations. Colors can be set only once, just after domain creation,
since recoloring isn't supported.

Based on original work from: Luca Miccio <lucmiccio@gmail.com>

Signed-off-by: Carlo Nonato <carlo.nonato@minervasys.tech>
Signed-off-by: Marco Solieri <marco.solieri@minervasys.tech>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/common/domain.c

@@ -34,6 +34,7 @@
 #include <xen/xenoprof.h>
 #include <xen/irq.h>
 #include <xen/argo.h>
+#include <xen/llc-coloring.h>
 #include <asm/p2m.h>
 #include <asm/processor.h>
 #include <public/sched.h>
@@ -1303,6 +1304,8 @@ void domain_destroy(struct domain *d)
 {
     BUG_ON(!d->is_dying);
 
+    domain_llc_coloring_free(d);
+
     /* May be already destroyed, or get_domain() can race us. */
     if ( atomic_cmpxchg(&d->refcnt, 0, DOMAIN_DESTROYED) != 0 )
         return;

xen/common/domctl.c

@@ -8,6 +8,7 @@
 
 #include <xen/types.h>
 #include <xen/lib.h>
+#include <xen/llc-coloring.h>
 #include <xen/err.h>
 #include <xen/mm.h>
 #include <xen/sched.h>
@@ -866,6 +867,15 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
                 __HYPERVISOR_domctl, "h", u_domctl);
         break;
 
+    case XEN_DOMCTL_set_llc_colors:
+        if ( op->u.set_llc_colors.pad )
+            ret = -EINVAL;
+        else if ( llc_coloring_enabled )
+            ret = domain_set_llc_colors(d, &op->u.set_llc_colors);
+        else
+            ret = -EOPNOTSUPP;
+        break;
+
     default:
         ret = arch_do_domctl(op, d, u_domctl);
         break;

xen/common/llc-coloring.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2024, Advanced Micro Devices, Inc.
  * Copyright (C) 2024, Minerva Systems SRL
  */
+#include <xen/guest_access.h>
 #include <xen/keyhandler.h>
 #include <xen/llc-coloring.h>
 #include <xen/param.h>
@@ -113,8 +114,7 @@ static void print_colors(const unsigned int colors[], unsigned int num_colors)
     printk(" }\n");
 }
 
-static bool __init check_colors(const unsigned int colors[],
-                                unsigned int num_colors)
+static bool check_colors(const unsigned int colors[], unsigned int num_colors)
 {
     unsigned int i;
 
@@ -196,7 +196,7 @@ void domain_dump_llc_colors(const struct domain *d)
     print_colors(d->llc_colors, d->num_llc_colors);
 }
 
-static void __init domain_set_default_colors(struct domain *d)
+static void domain_set_default_colors(struct domain *d)
 {
     printk(XENLOG_WARNING
            "LLC color config not found for %pd, using all colors\n", d);
@@ -233,6 +233,55 @@ int __init dom0_set_llc_colors(struct domain *d)
     return 0;
 }
 
+int domain_set_llc_colors(struct domain *d,
+                          const struct xen_domctl_set_llc_colors *config)
+{
+    unsigned int *colors;
+
+    if ( d->num_llc_colors )
+        return -EEXIST;
+
+    if ( !config->num_llc_colors )
+    {
+        domain_set_default_colors(d);
+        return 0;
+    }
+
+    if ( config->num_llc_colors > max_nr_colors )
+        return -EINVAL;
+
+    colors = xmalloc_array(unsigned int, config->num_llc_colors);
+    if ( !colors )
+        return -ENOMEM;
+
+    if ( copy_from_guest(colors, config->llc_colors, config->num_llc_colors) )
+    {
+        xfree(colors);
+        return -EFAULT;
+    }
+
+    if ( !check_colors(colors, config->num_llc_colors) )
+    {
+        printk(XENLOG_ERR "%pd: bad LLC color config\n", d);
+        xfree(colors);
+        return -EINVAL;
+    }
+
+    d->llc_colors = colors;
+    d->num_llc_colors = config->num_llc_colors;
+
+    return 0;
+}
+
+void domain_llc_coloring_free(struct domain *d)
+{
+    if ( !llc_coloring_enabled || d->llc_colors == default_colors )
+        return;
+
+    /* free pointer-to-const using __va(__pa()) */
+    xfree(__va(__pa(d->llc_colors)));
+}
+
 /*
  * Local variables:
  * mode: C

xen/include/public/domctl.h

@@ -1236,6 +1236,13 @@ struct xen_domctl_dt_overlay {
 };
 #endif
 
+struct xen_domctl_set_llc_colors {
+    /* IN LLC coloring parameters */
+    uint32_t num_llc_colors;
+    uint32_t pad;
+    XEN_GUEST_HANDLE_64(uint32) llc_colors;
+};
+
 struct xen_domctl {
     uint32_t cmd;
 #define XEN_DOMCTL_createdomain                   1
@@ -1325,6 +1332,7 @@ struct xen_domctl {
 #define XEN_DOMCTL_set_paging_mempool_size       86
 #define XEN_DOMCTL_dt_overlay                    87
 #define XEN_DOMCTL_gsi_permission                88
+#define XEN_DOMCTL_set_llc_colors                89
 #define XEN_DOMCTL_gdbsx_guestmemio            1000
 #define XEN_DOMCTL_gdbsx_pausevcpu             1001
 #define XEN_DOMCTL_gdbsx_unpausevcpu           1002
@@ -1391,6 +1399,7 @@ struct xen_domctl {
 #if defined(__arm__) || defined(__aarch64__)
         struct xen_domctl_dt_overlay        dt_overlay;
 #endif
+        struct xen_domctl_set_llc_colors    set_llc_colors;
         uint8_t                             pad[128];
     } u;
 };

xen/include/xen/llc-coloring.h

@@ -11,6 +11,7 @@
 #include <xen/types.h>
 
 struct domain;
+struct xen_domctl_set_llc_colors;
 
 #ifdef CONFIG_LLC_COLORING
 extern bool llc_coloring_enabled;
@@ -18,17 +19,21 @@ extern bool llc_coloring_enabled;
 void llc_coloring_init(void);
 void dump_llc_coloring_info(void);
 void domain_dump_llc_colors(const struct domain *d);
+void domain_llc_coloring_free(struct domain *d);
 #else
 #define llc_coloring_enabled false
 
 static inline void llc_coloring_init(void) {}
 static inline void dump_llc_coloring_info(void) {}
 static inline void domain_dump_llc_colors(const struct domain *d) {}
+static inline void domain_llc_coloring_free(struct domain *d) {}
 #endif
 
 unsigned int get_llc_way_size(void);
 void arch_llc_coloring_init(void);
 int dom0_set_llc_colors(struct domain *d);
+int domain_set_llc_colors(struct domain *d,
+                          const struct xen_domctl_set_llc_colors *config);
 
 #endif /* __XEN_LLC_COLORING_H__ */